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