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