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