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