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)(13,19)(14,18)(15,20)(17,27)(21,34)(22,31)(23,33)(25,30)(26,35)(28,36)(29,32)(37,39)(38,40) involution — undirected(1,3,5,4)(2,6,7,8)(9,11,15,23)(10,16,20,33)(12,25,28,38)(13,22,14,29)(17,34,35,39)(18,32,19,31)(21,26,37,27)(24,30,36,40)(9,12,15,28)(10,17,20,35)(11,21,23,37)(13,27,14,26)(16,30,33,40)(18,24,19,36)(22,38,29,25)(31,34,32,39)(1,4,5,3)(2,6,7,8)(10,18)(13,14)(16,31)(17,24)(19,20)(22,29)(25,38)(26,27)(30,34)(32,33)(35,36)(39,40)(2,7)(6,8)(9,13,15,14)(10,19,20,18)(11,22,23,29)(12,26,28,27)(16,31,33,32)(17,24,35,36)(21,25,37,38)(30,39,40,34)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.