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