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