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