One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,5)(4,7)(6,8)(9,10)(11,19)(12,17)(13,14)(15,18)(16,23)(20,22)(21,24)(25,26,31,28)(27,32,38,35)(29,39,37,33)(30,34,36,40)(2,3)(6,7)(9,11)(10,16)(12,20)(13,21)(14,22)(15,23)(17,24)(18,19)(25,27)(26,32)(28,35)(29,36)(30,37)(31,38)(33,34)(39,40) involution — undirected(1,2,5,3)(4,6,8,7)(9,12,15,13)(10,17,18,14)(11,20,23,21)(16,24,19,22)(25,26,31,28)(27,35,38,32)(29,33,37,39)(30,34,36,40)(1,3,5,2)(4,7,8,6)(9,13,15,12)(10,17,18,14)(11,21,23,20)(16,24,19,22)(25,28,31,26)(27,35,38,32)(29,39,37,33)(30,34,36,40)(1,4)(2,6)(3,7)(5,8)(9,11)(10,16)(12,20)(13,21)(14,22)(15,23)(17,24)(18,19)(25,29,31,37)(26,33,28,39)(27,36,38,30)(32,34,35,40)(9,14,15,17)(10,13,18,12)(11,22,23,24)(16,21,19,20)(25,30,31,36)(26,34,28,40)(27,37,38,29)(32,33,35,39)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.