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