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