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