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