One vertex per element, one color per generator, with an edge from x to x·s.
(2,6)(7,8)(9,10)(11,20)(12,23)(13,24)(14,19)(15,16)(17,22)(18,21)(25,26,31,28)(27,35,38,32)(29,39,37,33)(30,34,36,40)(1,2)(3,7)(4,8)(5,6)(9,11)(10,14)(12,21)(13,22)(15,19)(16,20)(17,18)(23,24)(25,27)(26,32)(28,35)(29,36)(30,37)(31,38)(33,40)(34,39) involution — undirected(1,3,5,4)(2,7,6,8)(10,16)(11,19)(12,22)(18,24)(26,28)(32,35)(33,39)(34,40)(9,12,15,22)(10,17,16,23)(11,21,19,13)(14,18,20,24)(25,28,31,26)(27,35,38,32)(29,39,37,33)(30,40,36,34)(1,3,5,4)(2,7,6,8)(9,13,15,21)(10,18,16,24)(11,22,19,12)(14,17,20,23)(25,29,31,37)(26,33,28,39)(27,36,38,30)(32,40,35,34)(1,4,5,3)(2,8,6,7)(9,14,15,20)(10,19,16,11)(12,18,22,24)(13,23,21,17)(25,30,31,36)(26,34,28,40)(27,37,38,29)(32,39,35,33)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.