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