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