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