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