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